Strong Acid Cation Exchange Resin Research Articles

Effect of Fractionation Columns on the Elution of Rare Earth Elements Recovered from Acid Mine Drainage

Rare earth elements (REE) can be found in expressive contents in different secondary sources, such as acid mine drainage (AMD). This work evaluated separation of light and heavy rare earth elements (REE) from an acid mine drainage (AMD) generated in a former uranium mine in Brazil by using ion exchange. This AMD presents pH 3.50, total REE content of 97 mg L−1 and 1.3 g L−1 of sulfate and was used in the REE loading experiments. Loading experiments were carried out in columns using a commercial strong acid cation (SAC) exchange resin. Elution was performed with 0.01 mol L−1 NH4EDTA in systems with one, two and three columns. Regarding the loading step, the resin presented a total loading capacity of 0.58 mmol g−1. The resin proved to be more selective for light REE with adsorption efficiency of 78% and 48% for heavy REE. Regarding elution, high efficiencies between 90 and 100% were achieved for REE. The final REE solution is approximately 10 times more concentrated in the liquor related to the acid mine water. Better fractionation results were achieved for the system with three columns. Although the complete separation of the REE into pure elements was not possible, two distinct fractions of heavy and light REE could be obtained, and La was completely separated from the other REE. In order to improve fractionation and separate the REE into individual ones, the concentrated fractions can proceed to subsequent ion exchange systems.

Removal of heavy metal ions from wastewater using ion exchange resin in a batch process with kinetic isotherm

Techniques such as selective ion exchange can be used to remove traces of heavy metals. The recently created resins provided quicker sorption kinetics and a high resin capacity for metal ions such as Lead (Pb²⁺), Copper (Cu²⁺), Zinc (Zn²⁺), Cadmium (Cd²⁺), and Nickel (Ni²⁺) ions. The elimination of Pb²⁺ and Cu²⁺ ions from aqueous solutions was examined in the current work. Purolite® C100, a strong acid cation-exchange resin, was used in experimental studies. Using packed-column chromatography, the impacts of operating factors on metal ion exchange were examined. These parameters included resin dose, initial pH, residence time, and metal ion concentration with ranges of 40 - 80 gs, 3 - 12, 30 - 90 min, and 50 -150 parts per million respectively. As part of exchange research, different doses of resin are brought into contact with a fixed volume of solution containing different concentrations and pHs of Pb²⁺ and Cu²⁺ ions for different periods. An Atomic Absorption Spectrophotometer (AAS) approach was used to measure the concentrations of metal ions. Experimental data on ion exchange were evaluated using Langmuir, Freundlich, and Temkin models.The results showed that there is a clear competition between lead and copper, as it was found that there is a convergence between the removal rates for both metals under the same conditions. The ion-exchange recovery of Cu approached 94.37 %, but Pb recovery was 92.9 % with Purolite® C100 resin dose range of 40 g to 80 g in the pH range of 3 to 12.

Construction and in vitro/in vivo evaluation of menantine hydrochloride oral liquid sustained-release drug delivery system

Objective The purpose of the present study was to formulate a menantine hydrochloride (MH) sustained-release suspension. Methods Menantine hydrochloride drug resin complex (MH-DRC) was prepared with strong acid cation exchange resin as carrier using water bath method. The MH-DRC was characterized using scanning electron microscopy, X-ray diffraction and infrared spectroscopy. The MH-coated microcapsule (MH-CM) with optimized formulation was further dispersed in a suitable medium to obtain a sustained-release suspension. The rats were given both the MH sustained-release suspension and the commercial MH sustained-release capsule by intragastric administration. The plasma concentration-time curves and related pharmacokinetic parameters were also investigated using a non-atrioventricular model. Results MH and ion-exchange resin were ionically bonded. AmberliteIRP®69 had a higher affinity for MH at the initial concentration of 5 mg·mL−1 and a reaction temperature of 25.0 ± 0.5 °C. In vitro drug release profile showed that both the drug resin complex and the coated microcapsules had a certain level of sustained-release effect. The t1/2 of MH sustained-release suspension was extended from 68.44 h to 72.79 h with the peak blood concentration being decreased to 3.56 μg·mL−1 and the Tmax extended to 12 h compared with the commercial MH sustained-release capsule. The concentration-time curve of the self-made MH sustained-release suspension was flattened and the average relative bioavailability (Fr ) was 116.65% compared with the commercial MH sustained-release capsules. Conclusions The findings showed that the MH sustained-release suspension was successfully formulated with acceptable pharmacokinetic indices for effective treatment of Alzheimer’s disease.

Rapid room temperature synthesis of Mn-doped perovskite quantum dots for white-light-emitting diodes

All-inorganic perovskite quantum dots (PQDs) have excellent photoelectric performance, such as high photoluminescence quantum yield (PLQY), narrow full width at half-maximum (FWHM), and emission spectra covering the visible light wavelength. The emission color can be tuned over the full visible spectral region making them promising for white-light-emitting diodes (WLEDs). Further control over the optical and magnetic properties of PQDs can be achieved through doping of transition metal ions such as Mn2+ ions. In this paper, a rapid doping method is employed at room temperature by using strong-acid cation-exchange resin during the metal ions doping process, which shortens the doping time, and Mn:CsPb(Cl/Br)3 QDs were obtained. By controlling the reaction time between strong-acid cation-exchange resin and PQDs, we achieve different levels of manganese doping, resulting in a new, to the best of our knowledge, fluorescence peak at 600 nm. The introduction of strong-acid cation-exchange resin preserves the integrity of the PQD structure, while completing the doping within 30 min. Due to the low cost and mild reaction conditions of resin, it is expected that the Mn:CsPb(Cl/Br)3 QDs can be mass-produced in large quantities. In addition, in order to provide high-quality white light emission, and prevent anion exchange reactions when mixed with CsPbBr3 QDs, the CsPbBr3 QDs are coated with silicon. Finally, by combining ultraviolet-light-emitting diodes (UVLEDs) with the aforementioned PQD mixture, this paper successfully fabricates WLEDs and demonstrates its excellent photoelectric performance. The constructed WLEDs produce warm white light with a high color rendering index (CRI) of 91 and a high correlated color temperature (CCT) of 5966 K, and the luminous efficacy (LE) of WLEDs is 41lmW−1.

Commercial turpentine oil enriched with α-terpineol using an acid heterogeneous catalyst

The hydration of α-pinene, limonene, β-pinene, and commercial turpentine oil in the presence of strong acidic cation exchange resin Amberlyst-15 was studied. The acid catalytic hydration was performed in a batch reactor, and the effect of solvent at various temperatures and reaction times was evaluated. The main hydration product obtained from α-pinene was α-terpineol with a yield of 36 % (4 h, 70 °C, 2-propanol as solvent); however, the selected catalytic system was even more active to obtain α-terpineol when β-pinene was used as a substrate, obtaining α-terpineol yield of 38 % in 2 h of reaction. For the hydration of turpentine (70 °C, turpentine:water:2-propanol mass ratio of 1:0.5:2, 15 % w/w catalyst) the composition of reaction mixture after 4 h was 35 % w/w of α-terpineol, 8 % w/w of α-pinene, and 0.5 % w/w of β –pinene, which correspond to a final content of α-terpineol similar to the concentration obtained when α-pinene was used as a substrate (36 % w/w).

Role of some structural features in EPS from microalgae stimulating collagen production by human dermal fibroblasts

ABSTRACTExopolysaccharides (EPS) from the microalgae Porphyridium cruentum, Chrysotila dentata, Pavlova sp., Diacronema sp., Glossomastix sp., Phaeodactylum tricornutum, and Synechococcus sp. were isolated and depolymerized. First, EPS were submitted to a high pressure pre-treatment step, followed by a solid acid-catalyzed hydrolysis step carried out in a batch or recycle fixed-bed reactor, using a strong acidic cation-exchange resin. Twenty-eight different EPS forms were thus obtained. After characterization of their main structural features (weight- and number-averaged molecular weight, polydispersity index, sulfate and uronic acid contents), we investigated the structure–function relationship of their pro-collagen activity. We found that native microalgae EPS were able to inhibit until 27% of human matrix metalloproteinase-1 (MMP-1) activity while the depolymerized forms were able to enhance collagen production by two different human fibroblast lines, used as cell models due to their major role in dermal collagen biosynthesis. The most active EPS forms, obtained by depolymerization in the recycle fixed-bed reactor of D. ennorea and Glossomastix sp. EPS, led to 390% increase in collagen production. Finally, principal component (PCA) and Pearson analyses indicated that MMP-1 inhibition was strongly correlated to the sulfate group content of EPS whereas collagen production by fibroblasts was mostly related to their proportion of low molecular weight polysaccharides (<10 kDa). Uronic acid content of EPS was also shown essential but only if the size of EPS was reduced in the first place. Altogether, these results gave new insights of the dermo-cosmetic potential of microalgae EPS as well as the key parameters of their activity.

Sorption of Lead, Zinc and Copper from Simulated Wastewater by Amberlite Ir-120 Resin

The presence of heavy metals in the environment is major concern due to their toxicity. In the present study a strong acid cation exchange resin, Amberlite IR 120 was used for the removal of lead, zinc and copper from simulated wastewater. The optimum conditions were determined in a batch system of concentration 100 mg/L, pH range between 1 and 8, contact time between 5 and 120 minutes, and amount of adsorbent was from 0.05 to 0.45 g/100 ml. A constant stirring speed, 180 rpm, was chosen during all of the experiments. The optimum conditions were found to be pH of 4 for copper and lead and pH 6 for zinc, contact time of 60 min and 0.35 g of adsorbent. Three different temperatures (25, 40 and 60°C) were selected to investigate the effect of adsorption temperature on heavy metals adsorption onto Amberlite IR. The equilibrium data were analyzed by the Langmuir and Freundlich isotherms. The thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes were calculated. Moreover, in order to understand the heavy metal extraction kinetics in the presence of Amberlite IR 120, the ion exchange kinetics was also studied. The ion exchange kinetics data were regressed by the pseudo first-order, second-order models. The results obtained show that the Amberlite IR 120 strong acid cation exchange resin performed well for the removal of lead, zinc and copper.

3D printed heterogeneous cation exchange membrane processed using stereolithography

AbstractMembrane chemistry belongs to the field in which 3D printing can advantageously also be used because of enabling the production of prototypes with precisely defined dimensions. The presented work aimed to develop new polymeric compositions for heterogeneous cation exchange membranes manufactured using stereolithography (SLA) from commercially available materials. Three types of photo‐curable thermoset resins (acrylic resin and two types of epoxy resins) were used as polymer matrixes in combination with strong acid cation exchange resin (CER) powder. The membrane production consisted of several stages, namely mixing the photo‐curable resin with finely ground CER powder, processing using SLA, and appropriate post‐curing using UV light and elevated temperature. The work aimed to monitor the influence of the photo‐curable resin type and post‐curing on the microstructural, electrochemical, and mechanical properties of resulting membrane objects. The results revealed that heterogeneous cation exchange membranes could be processed using SLA from the mixture of the acrylic photo‐curable resin and CER powder (weight ratio of 60/40) without the need for post‐curing. These products exhibited high permselectivity (93%), high ion exchange capacity (2.23 meq⋅g−1), and sufficiently low electrical resistance (2200 Ω⋅cm), which predetermines them for efficient electrophoretic separation.

Proof-of-Concept study of ion-exchange method for the recycling of LiFePO4 cathode

Recycling spent lithium iron phosphate (LFP) cathodes in an economically sustainable way remains a great challenge due to their low-value elemental composition. Thus, both low-cost technology together with a high-value product are critical for the recovery of the LFP materials. In this study, the commercially mature ion-exchange (IX) method was explored to recover Li from LFP material for the first time. The feasibility of Li-H and Li-K IX reactions using strong and weak acid cation exchange resins was systematically investigated from the thermodynamic and kinetic perspectives. Different organic and inorganic acids were explored to obtain the feeding solution. The IX efficiency was greatly affected by the pH of the feeding solutions. Oxalic acid leaching solution with mild pH value and low iron impurity were determined to be the optimal feeding solution for IX reaction. The kinetics of IX and regeneration reaction were fast, and the resins can be reused several times without loss of IX capacity. Along with the P element remaining in the leaching solution, the Li-K IX reaction delivered a potential product of multi-elemental fertilizer. This simple and economical technology provides a practical recycling strategy for the spent LFP batteries.

Electrified Ion Exchange Enabled by Water Dissociation in Bipolar Membranes for Nitrogen Recovery from Source-Separated Urine.

Ion exchange (IX) is a promising technology for selective nitrogen recovery from urine; however, IX requires chemical-intensive regeneration that escalates energy consumption and carbon emissions. To overcome this barrier, we demonstrated and investigated a novel electrified IX stripping process (EXS) enabling electrochemical in situ IX regeneration with simultaneous ammonia stripping. EXS combines a weak acid cation exchange resin (WAC) to concentrate ammonia, a bipolar membrane to produce protons for WAC regeneration, and membrane stripping to recover the eluted ammonium from WAC. We observed over 80% regeneration (elution from resin) and recovery (membrane stripping) efficiencies during multiple adsorption-recovery cycles with synthetic and real urine. Comparing WAC with a strong acid cation exchange resin illustrated the critical role of the proton affinity of resin moieties in regulating resin regenerability and conductivity in EXS, which we distinguished from the rationale for material choice in electrodeionization. Compared to other electrochemical recovery methods using unamended wastewater as an electrolyte, EXS enabled control of electrolyte composition during recovery by separating and equalizing influent ammonium via WAC-mediated removal. This electrolyte engineering facilitated tunable EXS energy efficiency (100-300 MJ/kg N). This study informs the design of electrified, intensified systems that enable decentralized nitrogen recovery from urine.

A novel approach for synchronous transformation and extraction of psoralen from fig (Ficus carica L.) leaves based on polarity of different macroporous adsorption resins

In this study, using fig leaves as materials, strong acidic cation exchange resin of D072 with –SO3H functional group was selected as catalyst to promote the conversion of psoralen-glucoside (PO) to psoralen (PSO), and the strong acidic cation exchange resin transformation method (SACERTM) was developed for efficient extraction of PSO from fig leaves. Under the optimized extraction conditions, the yield of PSO was 36.74 mg/g. The transformation efficiency of PO to PSO reached 70.41% using 2 g of D072 resin as catalyst. Then, PSO in fig extract was enriched efficiently by X-5 macroporous adsorption resin (MAR). After eluting with 14-fold of column volume of 70% ethanol at 0.64 BV/h of elution flow rate, the purity of PSO was 24.8-fold higher than before enrichment. The results show that SACERTM combined with MAR purification is an efficient method for extracting and enriching PSO from fig leaves.

Adsorption and possibility of separation of heavy metal cations by strong cation exchange resin

This work is devoted to the study of the adsorption of strontium, yttrium, and zirconium ions by the strong acid cation exchange resin Dowex HCR-s/s. The adsorption of strontium, yttrium, and zirconium ions in batch and dynamic conditions from individual solutions of the studied elements, as well as from their mixture, was studied. It was shown that the dependences of the adsorption of strontium, yttrium, and zirconium ions on agitation time fit well with the pseudo-first-order and Elovich equations. Equilibrium adsorption of all three cations can be described with Langmuir's theory. Column adsorption has shown that Dowex HCR-s/s adsorb all three investigated cations from the acidic medium. The inductively coupled plasma mass spectrometry (ICP-MS) proves that separation of these cations using Dowex HCR-s/s is possible only in highly dilute solutions at a concentration of 10 ng/ml of each element. The basis of separation will be a higher rate of adsorption of tetravalent zirconium, compared with strontium and yttrium. As the concentration of the investigated elements increases to 100 ng/ml, all three cations are adsorbed by the resin in equal amounts and can be separated only using special eluents, such as Ca-EDTA.

Recovery of rare earth elements from uranium leach liquors by adsorption with diglycolamic acid ligands and ionic liquids

A series of extraction chromatographic resins containing various phosphorus-containing and DGA-based extractants and ionic liquids was synthesized and their sorption characteristics for rare earth elements (REE) in sulfate solutions were studied. The effects of the type and content of ionic liquid in the stationary phase as well as solid support type on the sorption capacity of the resins for La, Nd and Dy were evaluated. It was shown that the quantity of the stationary organic phase in the resins was 30–35% independent of the matrix type. In the case of the DODGAA: TODGA: [C4mim][Tf2N] system, the matrix type did not affect the resin capacity for REE in sulfuric acid solutions. Acidity of the aqueous phase was one of the most important factors affecting lanthanides sorption from sulfate solutions. The capacity of the sorbents for lanthanides decreased sharply with the increase of acidity of the solution, this decrease was stronger for light REE. The process of REE separation from uranium leach liquors was studied using real leach liquors after separation of uranium. It was shown that a resin based on hydrophobic silica gel impregnated by DODGAA:TODGA:[C4mim][Tf2N] mixture can be recommended for concentration and primary separation of lanthanides from multicomponent industrial solutions. The advantage of this sorbent is a high selectivity for REE over macro amounts of Al and Fe as compared with strong acid cation exchange resins and phosphorus-containing organic extractants, which are widely used for preconcentration. Using this sorbent for selective recovery of REE from uranium leach liquors provided concentration factors of 10–15 for light REE group and 150–300 for heavy REE group.

Synergistic effects for fast co-pyrolysis of strong-acid cation exchange resin and cellulose using Py-GC/MS

This study aimed to investigate the co-pyrolysis characteristics of strong-acid cation exchange resin (Amberlyst-15, denoted as A15) and cellulose (CE), in which the existing synergistic interaction effects were uncovered. Crucial variables including pyrolytic temperature, A15-to-CE mass ratio and heating rate were taken into consideration. The levoglucosenone (LGO) production from CE and inorganic sulfur-containing species release from functional sulfonic acid groups of A15 were enhanced in a temperature range of below 400 °C. In this regard, the LGO yield achieved approximately 7 wt% at 300 °C with A15-to-CE mass ratio of 1:1. Relatively, elevating the temperature and heating rate accelerated the A15 self-decomposition and small molecule fragments restructuring to give much more monocyclic and polycyclic aromatics. Noticeably, organic sulfur-containing compounds also were produced in an unignorable amount of 8.2% under preset conditions of pyrolytic temperature of 700 °C and heating rate of 20,000 °C/s. The plausible pathway for the co-pyrolysis transformation of A15 and CE was also proposed on the basis of experimental results. The present work will provide a probable and feasible strategy for the high-value utilization of biomass and waste ion-exchange resins, particularly in the aspect of the generation of certain chemicals.

Kinetics and adsorption isotherm of ammonia uptake by cation exchange resins and treatment of mixed aqueous lactate–ammonia by Mg–Al layered double oxide and the resins

The proliferation of pluripotent stem cells in mass cell culture is hindered by the release of cell metabolites such as lactate and ammonia. In this work, a porous strong-acid cation exchange resin (PK216LH) and Mg–Al layered doubled oxide (LDO) were used to take up NH4+ and lactate, respectively. Initially, PK216LH could take up NH4+ from an aqueous solution. The uptake of NH4+ by PK216LH followed pseudo-second-order kinetics and corresponded to the Langmuir adsorption isotherm, with an apparent activation energy of 28.2 kJ/mol and a maximum adsorption amount of 1.38 mmol/g. The simultaneous use of Mg–Al LDO and PK216LH could not sufficiently take up lactate and NH4+. In contrast, the individual use of Mg–Al LDO and PK216LH in two stages enabled efficient removal of lactate and NH4+.

A facile modification of cation exchange resin by nano-sized goethite for enhanced Cr(VI) removal from water

ABSTRACT A novel macroporous strong acidic cation exchange resin (D001) modified by nano-sized goethite (nFeOOH@D001) was fabricated by using a facile ethanol dispersion and impregnation method, and its efficiency for Cr(VI) removal was tested thereafter. Due to the dispersing effect of ethanol, FeOOH particles of 20–150 nm were coated on the D001 surfaces. The nFeOOH@D001 obtained a Cr(VI) removal efficiency and capacity of 80.2% and 7.4 mg/g respectively, 5 times and 8 times higher than that of the pristine D001. The Cr(VI) removal by nFeOOH@D001 followed the pseudo second-order kinetics and the Langmuir adsorption model. Column experiments also demonstrated that the nFeOOH@D001 exhibited a much better ability to remove Cr(VI) as compared to the D001. Additionally, the nFeOOH@D001 showed a potential for reusability and renewability. The adsorbed nFeOOH@D001 could be easily desorbed by 0.1 M acetic acid and a reuse efficiency of 92.7% could be maintained after 4 desorption–adsorption cycles. The used nFeOOH@D001 could be eluted by 0.1 M HCl to remove nFeOOH, and the renewed D001 could be recoated by nFeOOH and achieved a regeneration rate of 97.8% for Cr(VI) removal. The above results indicated that nano-sized goethite modification is a promising method to endow D001 with the ability to remove Cr(VI) from water.

Adsorption Thermodynamics and Kinetics of Resin for Metal Impurities in Bis(2-hydroxyethyl) Terephthalate.

Adsorption of heavy metals from degraded of Polyethylene terephthalate (PET) products by strong cation exchange resin AmberliteIR-120 under optimized conditions toward the selectivity removal of metals are in the following order: Al3+ > Zn2+ > Mg2+ > Fe2+ > Ni2+. Therefore, kinetic and adsorption isotherm models were applied for fitting experimental data. Comparatively, adsorption isotherm study revealed that Langmuir isotherm model better fits adsorption on surface of resin over than the Freundlich model. In summary, AmberliteIR-120 strong acid cation exchange resin can be used as an efficient adsorbent for heavy metals removal from depolymerized products bis(2-hydroxyethyl) terephthalate.

Mass transfer process and separation mechanism of four 5′-ribonucleotides on a strong acid cation exchange resin

5′-ribonucleotides including adenosine 5′-monophosphate (AMP), cytidine 5′-monophsphate (CMP), guanosine 5′-monophosphate (GMP) and uridine 5′-monophosphate (UMP) have been widely used in the food and pharmaceutical industries. This work focused on the assessment of mass transfer process and separation mechanism of four 5′-ribonucleotides and counter-ion Na+ on the strong cation exchange resin NH-1. The intraparticle diffusion was determined as the rate-limiting step for the mass transfer of AMP, CMP, GMP, and Na+ on the resin NH-1 through the Boyd model. Meanwhile, a homogeneous surface diffusion model (HSDM) combing ion exchange and physical adsorption was proposed and tested against adsorption kinetic data in the batch adsorption systems. The fixed-bed film-surface diffusion model based on the HSDM was then developed and successfully predicted the concentration profiles of 5′-ribonucleotides and the change of pH at the outlet of the fixed-bed in the dynamic adsorption and separation process. Finally, the separation mechanism of 5′-ribonucleotides was presented combining model prediction and experimental results. The separation of UMP, GMP and CMP were mainly based on their differences in isoelectric points, while that of AMP and CMP were lied with the discrepancy of their physical adsorption binding capacity with the resin NH-1.

Recycle of vanadium from aluminum slag of ferrovanadium

Vanadium is a rare chemical element and it primarily comes from the by-product of other minerals. In this study, the material source mainly comes from vanadium-rich aluminum slag. This experiment aims to separate vanadium and other impurities, such as aluminum and zirconium. First, the slag was dissolved in the sodium hydroxide solution at pH value 13, and part of the alumina was precipitated. After removing the precipitation, the strong acid cation exchange resin, Dowex® G26, was added to eliminate the remaining impurities. In this procedure, the parameter of reaction time, the mass of ion exchange resin and pH value were supplied. Moreover, the adsorption isotherms described by means of the Langmuir and Freundlich isotherms were used to investigate the ion-exchange behaviors of vanadium. To sum up, this study will provide the best conditions of ion exchange to get high purity about 95% of vanadate.

Selective Separation of Radium and Actinium from Bulk Thorium Target Material

A complete scheme for the selective separation of actinium and radium isotopes from bulk 232Th target material will be presented. The process may be applicable to the production of 225Ac and 227Ac via proton spallation on thorium targets. Thorium metal is dissolved in sulfuric acid with small amounts of HF. Actinium and radium are retained on cation exchange resin from the sulfate medium, while neutral and anionic thorium sulfate complexes are rejected. Targeting the minor components (Ac,Ra) allows use of much smaller chromatographic columns than traditional nitrate based systems which target the bulk thorium. Additionally, the primary separation is performed from 0.1M Th, 0.6M sulfate, pH 1-2 instead of the more corrosive 3-8M HNO3 typically employed in solvent extraction or anion exchange based thorium separations. Actinium and radium are recovered from the cation exchange resin in a small volume of 5M HNO3 and directly purified via extraction chromatography with UTEVA and DGA resins without feed adjustment or evaporation. The radium fraction can be further processed following ingrowth of 225Ac from 225Ra to produce additional 225Ac free from any potential 227Ac impurity. The flowsheet has been tested at the Canadian Nuclear Laboratory (CNL) on 25 gram solid thorium targets irradiated at Fermi Lab. -Bond, A.H., Horwitz, E.P., McAlister, D.R., 2006. A Multicolumn Selectivity Inversion Generator for the Production of High Purity Actinium-225 for Use in Therapeutic Nuclear Medicine, United States patent number 7,087,206. (Licensed to NorthStar Medical Radioisotopes) -D.R. McAlister, E.P. Horwitz, “Selective Separation of Radium and Actinium from Bulk Thorium Target Material on Strong Acid Cation Exchange Resin from Sulfate Media,” Applied Radiation and Isotopes, 140, 18-23 (2018).